Conventionally, elevators are equipped with emergency safety devices in which a speed governor is activated and presses a wedge-shaped damper against a guide rail when a descent speed of a hoisted body such as a car or a counterweigh exceeds a fixed velocity, to brake the hoisted body using frictional force that arises between the damper and the guide rail.
However, braking force on the hoisted body varies due to differences in the coefficients of friction between the damper and the guide rail. In other words, even if a normal component of reaction with which a braking surface of the damper pushes against a braking surface of the guide rail is constant, the braking force, i.e., frictional force, changes depending on the state of the braking surfaces or braking speed. Thus, one problem has been that because the braking speed is fast and frictional force is small when deceleration starts, the deceleration rate is low, and because braking speed becomes slow and the frictional force becomes large as deceleration finishes, deceleration rate increases rapidly.
In consideration of such conditions, conventional emergency safety devices have been proposed that are equipped with a mechanism by which dimensions of a wedge-shaped damper in a direction that is perpendicular to a braking surface of a guide rail change so as to equal braking force (see Patent Literature 1, for example). In the conventional emergency safety devices, the dimensions of the damper change in response to changes in braking force to change the pressing force from an elastic body. Here, the pressing force of the elastic body changes so as to cancel out fluctuations in braking force, such that the braking force is kept constant. In this manner, the conventional emergency safety devices operate automatically to suppress fluctuations in braking force when changes in braking force are detected, suppressing changes in the deceleration rate.